When creating a new uvmap for an object the previous uvmaps are included. How do I start without them?
Creating a new uvmap, duplicates the selected uvmap.

You can change any uvmap layout without altering any other uvmaps, just choose a different mapping type from the unwrap menu or adjust the uv positions the way you want them.

If you want to completely reset a uvmap - in edit mode select all A and then press U and select Reset.